Vacuum Pump Setup

If your MADCAP RACE ENGINE is equipped with a
Vacuum Pump please read this entire sheet!

Install a vacuum gauge on your engine. Remove
the 1/8-inch pipe plug located on the back of
your valve cover. Then screw in the appropriate
fitting that allows you to use your vacuum gauge.
If you are working on a brand new
engine or one you just got back from MADCAP for
a freshen, MAKE SURE YOU HAVE ADDED OIL. Start
your engine and check the timing, make sure all
cylinders are firing. Take a vacuum reading from
your gauge.

On your Post-Dyno inspection report that came
with your engine you will see the max vacuum setting.
We have tried to set your pump to the proper setting.
When altitude changes so can your vacuum reading.
We recommend your vacuum gauge be located where
the driver can safely monitor during a run down
the track. Engine Vacuum is a great way to monitor
how your engine is performing.

If vacuum is not within specs on your sheet,
you can adjust by following these simple instructions.
Or Call us. 1-800-349-8590

Unscrew the cap on the Vacuum Regulator located
on your Intake Manifold, in front of the distributor.
BE very careful, this may be warm and there are
some small parts involved. After removing the
cap, remove spring and plunger. To INCREASE Vacuum
add a small washer under the spring assembly.
To LOWER vacuum remove a small washer from under
spring assembly. Screw cap back on valve, make
sure O-ring is in good shape and clean. DO NOT
OVER TIGHTEN.

You may find your engine runs better with more
vacuum. Be VERY CAREFUL. If you run more vacuum
than the max we recommend SEVERE INTERNAL DAMAGE
may occur.

THINGS TO LOOK FOR ON YOUR GAUGE
You are looking for your gauge
to increase as you run or to reach a reading
and stay steady.

During a run; if you notice the pressure decrease
slightly as RPM increases or if you see a Rapid
Spike in your reading this is a sign of Detonation.
(This is bad) Retard your timing before making
any more runs.

If your vacuum suddenly drops and does not recover
this may mean a pump, pulley or belt failure or
a massive air leak due to a blown seal or gasket.
In some cases this may also indicate internal
engine damage. The first thing to do is check
for an air leak. Remove your gauge line; then
cap the hose that goes from your pump to your
breather tank. Blow compressed air into the fitting
where you removed your vacuum gauge. BE VERY CAREFUL.
DO NOT blow too much air; it takes very little
pressure to check for leaks. After putting air
into the valve cover plug the fitting with your
finger and LISTEN for any air leaks. Get some
help so you have people on the bottom (oil pan)
and both sides of your engine. Any air leak at
all can make a BIG difference. The most common
place is valve cover gaskets. Repair air leak
if you find one and then re-start your engine
and check gauge reading.

If you hear no vacuum leak then you must remove
the spark plugs and perform a leak down test on
your engine.